package com.techsoft.utils;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class DesUtil {
	private final static String DES = "DES";

	/**
	 * Description 根据键值进行加密
	 * 
	 * @param data
	 * @param key
	 *            加密键byte数组
	 * @return
	 * @throws UtilException
	 * @throws Exception
	 */
	public static String encrypt(String data, String key) throws UtilException {
		byte[] bt = encrypt(data.getBytes(), key.getBytes());
		String strs = HexUtil.encodeHexStr(bt);
		return strs;
	}

	/**
	 * Description 根据键值进行解密
	 * 
	 * @param data
	 * @param key
	 *            加密键byte数组
	 * @return
	 * @throws UtilException
	 */
	public static String decrypt(String data, String key) throws UtilException {
		if (data == null)
			return null;

		try {
			byte[] buf = HexUtil.decodeHex(data.toCharArray());
			byte[] bt = decrypt(buf, key.getBytes());
			return new String(bt);
		} catch (Exception e) {
			throw new UtilException(e.getMessage());
		}
	}

	/**
	 * Description 根据键值进行加密
	 * 
	 * @param data
	 * @param key
	 *            加密键byte数组
	 * @return
	 * @throws UtilException
	 */
	private static byte[] encrypt(byte[] data, byte[] key) throws UtilException {
		try {
			// 生成一个可信任的随机数源
			SecureRandom sr = new SecureRandom();

			// 从原始密钥数据创建DESKeySpec对象
			DESKeySpec dks = new DESKeySpec(key);

			// 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
			SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
			SecretKey securekey = keyFactory.generateSecret(dks);

			// Cipher对象实际完成加密操作
			Cipher cipher = Cipher.getInstance(DES);

			// 用密钥初始化Cipher对象
			cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);

			return cipher.doFinal(data);
		} catch (Exception e) {
			throw new UtilException(e.getMessage());
		}
	}

	/**
	 * Description 根据键值进行解密
	 * 
	 * @param data
	 * @param key
	 *            加密键byte数组
	 * @return
	 * @throws UtilException
	 */
	private static byte[] decrypt(byte[] data, byte[] key) throws UtilException {
		try {
			// 生成一个可信任的随机数源
			SecureRandom sr = new SecureRandom();

			// 从原始密钥数据创建DESKeySpec对象
			DESKeySpec dks = new DESKeySpec(key);

			// 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
			SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
			SecretKey securekey = keyFactory.generateSecret(dks);

			// Cipher对象实际完成解密操作
			Cipher cipher = Cipher.getInstance(DES);

			// 用密钥初始化Cipher对象
			cipher.init(Cipher.DECRYPT_MODE, securekey, sr);

			return cipher.doFinal(data);
		} catch (Exception e) {
			throw new UtilException(e.getMessage());
		}
	}

}
